Method of constructing a structure for electric cable introduction in an explosion-proof facility

ABSTRACT

An electric cable introduction structure in an explosion-proof facility includes a relay terminal box, a rack and an explosion-proof building. The relay terminal box connects an external electric cable to an internal electric cable. The rack is provided with the relay terminal box and sealed from the relay terminal box. Also, the rack relays the internal electric cable introduced from the relay terminal box. The explosion-proof building is provided with the rack outside and sealed from the rack and receives the internal electric cable from the rack.

[0001] This is a Divisional Application of U.S. patent application Ser. No. 09/866,846, filed May 30, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an electric cable introduction structure in an explosion-proof facility where a gas turbine is installed.

[0004] 2. Description of the Related art

[0005] As operating equipment in a facility, a gas turbine may be present in a thermal power plant. The gas turbine is installed inside an explosion-proof building which should be shielded from the outside. The explosion-proof building is built to have an easy disassembly structure to easily expose the gas turbine for maintenance of the gas turbine. Also, electric cables are introduced from the outside of the explosion-proof building into the inside thereof through buried electric cable pipes provided under the explosion-proof building so as not to hinder the disassembly of the explosion-proof building.

[0006]FIG. 1 is a schematic front view showing a conventional installation situation of the gas turbine. In FIG. 1, an explosion-proof facility is composed of a foundation section 1 b, a floor section 2 on the foundation section 1 b, a gas turbine 3, an air inlet section 3 a, an explosion-proof building 4, a first rack 5, a generator 51 and a steam turbine 52. The gas turbine 3 is installed on the floor section 2 inside the explosion-proof building 4 and is blocked off from the outside of the building 4. The electric cables are introduced from the outside of the explosion-proof building 4 into the inside thereof through buried pipes provided in the floor section 2.

[0007]FIG. 2 is a schematic perspective view showing an arrangement example of the first rack 5 and the explosion-proof building 4 in the conventional explosion-proof facility. Referring to FIG. 2, the floor section 2, the explosion-proof building 4 and the first rack 5 are shown. An electric cable trench 2 a is provided for the side of the floor section 2. Buried pipes 73 are buried in the floor section 2. A terminal box 70 is arranged in the electric cable trench 2 a, and an electric cable tray 71 is provided for the terminal box 70 inside the electric cable trench 2 a. Heat-resistant external electric cables 70 a are introduced into the terminal box 70 from a lower portion in the trench 2 a. Heat-resistant external electric cables 72 are arranged from the terminal box 70 onto the electric cable tray 71, and are introduced into the explosion-proof building 4 through the buried pipes 73. In the explosion-proof building 4, the heat-resistant external electric cables 72 are connected with internal electric cables 75 in a relay terminal box 74. For example, the internal electric cable 75 is formed of a heat-resistant electric cable such as Teflon electric cable.

[0008]FIG. 3 is a schematic side view showing the internal structure of a conventional explosion-proof facility 200. The explosion-proof facility 200 is composed of an outer building 1 a built on the foundation section 1 b. For example, a crane is attached to the outer building 1 a and is used for the disassembly of the explosion-proof building 4. The outer building 1 a forms an inner space 1 c. The floor section 2 is built on the foundation section 1 b in the inside space 1 c. The gas turbine 3, the explosion-proof building 4, the first rack 5 and a second rack 6 are installed on the floor section 2. The explosion-proof relay terminal box 74 is installed inside the explosion-proof building 4.

[0009] The floor section 2 is provided with the electric cable trench 2 a. The electric cable trench 2 a has a depth and a width so that a maintenance person can walk in the electric cable trench 2 a. The electric cable tray 71 is installed in the electric cable trench 2 a. The buried pipes 73 are provided in the floor section 2 to connect the electric cable trenches 2 a and an explosion-proof space 4 a in the explosion-proof building 4. The external electric cables 72 on the electric cable tray 71 are introduced into the relay terminal box 74 in the explosion-proof space 4 a through the buried pipe 73. The external electric cables 72 are connected with the internal electric cables 75 in the relay terminal box 74, and the internal electric cables 75 are distributed from the relay terminal box 74 in the explosion-proof building 4.

[0010] It should be noted that the buried pipe 73 is filled with sealing material such as silicon resin to shield the inside of the explosion-proof building 4 from the outside thereof, after introduction of the external electric cable 72. Also, it should be noted that the explosion-proof building 4 and the first and second racks 5 and 6 are disassembled at the time of the maintenance of the gas turbine 3. After the maintenance of the gas turbine 3 is completed, the explosion-proof building 4 and the first and second racks 5 and 6 are reassembled. In the explosion-proof facility 200 in which such disassembly and re-assembly are expected, the electric cables cannot be introduced into the explosion-proof building 4 through the wall of the building 4. Therefore, the structure is adopted in which the buried pipe 73 is buried and the electric cables are introduced through the buried pipe 73.

[0011] In the conventional structure for introduction of the electric cables into the explosion-proof facility, the positions where the buried pipes 73 are buried needs to be determined in the step of the foundation work for the foundation section 1 b and the floor section 2. However, it is difficult to determine the positions where the buried pipes are buried in the step of the foundation work. Therefore, buried pipes are provided for all the positions where the electric cables will be introduced. Some of the buried pipes are selected and used in accordance with the progress of the installation of the gas turbine. However, there are many buried pipes not actually used. Also, the unused buried pipes cause an increase in construction cost. Moreover, interference increases between the many buried pipes and the reinforcing bars of the concrete, and causes an increase of construction cost to prevent the interference.

SUMMARY OF THE INVENTION

[0012] Therefore, an object of the present invention is to provide an structure for introduction of electric cables into an explosion-proof facility in which work for the introduction of the electric cables is not required in the step of foundation work.

[0013] Another object of the present invention is to provide an structure for introduction of electric cables into an explosion-proof facility in which introduction routes of the electric cables can be determined at a necessary timing.

[0014] In an aspect of the present invention, an electric cable introduction structure in an explosion-proof facility includes a relay terminal box, a rack and an explosion-proof building. The relay terminal box connects an external electric cable to an internal electric cable. The rack is provided with the relay terminal box and sealed from the relay terminal box. Also, the rack relays the internal electric cable introduced from the relay terminal box. The explosion-proof building is provided with the rack outside and sealed from the rack and receives the internal electric cable from the rack.

[0015] The electric cable introduction structure may further include a first sealing section which passes the internal electric cable from the relay terminal box into the rack while sealing the rack from the relay terminal box. In this case, the first sealing section may be provided to penetrate a front wall of the rack. In addition, the first sealing section may be provided on the front wall of the rack below the relay terminal box. Alternatively, the first sealing section may be provided on the front wall of the rack above the relay terminal box.

[0016] Also, the first sealing section may be provided to penetrate a side wall of the rack. In this case, the first sealing section may be provided on the side wall of the rack below the relay terminal box. Alternatively, the first sealing section may be provided on the side wall of the rack above the relay terminal box.

[0017] The electric cable introduction structure may further include a trench which is provided on a side of the explosion-proof building and in which the external electric cable is arranged. In this case, the external electric cable is introduced from the trench into the relay terminal box through a pipe. In this case, when the electric cable introduction structure further includes a floor section on which the explosion-proof building and the rack are built, the pipe may be arranged along a surface of the floor section from the trench. Alternatively, the pipe may be arranged in the floor section to the trench.

[0018] Also, the electric cable introduction structure may further include a second sealing section which passes the internal electric cable from the rack into the explosion-proof building while sealing the explosion-proof building from the rack. In this case, the second sealing section may be provided to penetrate a wall between the rack and the explosion-proof building.

[0019] Also, the explosion-proof building accommodates a gas turbine.

[0020] Also, in the electric cable introduction structure, a plurality of relay terminal boxes may be provided for the rack. Also, a plurality of racks may be provided for the explosion-proof building.

[0021] Also, the rack is desirably not disassembled when the explosion-proof building is disassembled.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a front view showing the conventional internal structure of an explosion-proof facility containing a gas turbine;

[0023]FIG. 2 is a perspective view showing the peripheral structure of an explosion-proof building in the conventional explosion-proof facility;

[0024]FIG. 3 is a schematic side view showing the internal structure of an explosion-proof facility;

[0025]FIG. 4 is a schematic front view showing the internal structure of an explosion-proof facility containing a gas turbine according to a first embodiment of the present invention;

[0026]FIG. 5 is a schematic side view showing the internal structure of the explosion-proof facility according to the first embodiment of the present invention;

[0027]FIG. 6 is a schematic perspective view showing the peripheral structure of an explosion-proof building in the explosion-proof facility according to the first embodiment of the present invention;

[0028]FIG. 7 is a front view of a relay terminal box provided for a rack according to the first embodiment of the present invention;

[0029]FIG. 8 is a side view of the relay terminal box according to the first embodiment of the present invention;

[0030]FIG. 9 is a plan view showing the internal structure of the explosion-proof facility according to the first embodiment of the present invention;

[0031]FIG. 10A is a side view of the internal structure of the explosion-proof facility according to a modification the first embodiment of the present invention;

[0032]FIG. 10B is an expanded view of the rack in the explosion-proof facility according to the modification the first embodiment of the present invention;

[0033]FIG. 11 is a schematic front view showing the internal structure of an explosion-proof facility containing a gas turbine according to a second embodiment of the present invention;

[0034]FIG. 12 is a schematic side view showing the internal structure of the explosion-proof facility according to the second embodiment of the present invention;

[0035]FIG. 13 is a schematic perspective view showing the peripheral structure of an explosion-proof building in the explosion-proof facility according to the second embodiment of the present invention;

[0036]FIG. 14 is a front view of a relay terminal box provided for a rack according to the second embodiment of the present invention;

[0037]FIG. 15 is a side view of the relay terminal box according to the second embodiment of the present invention;

[0038]FIG. 16 is a front view of a relay terminal box provided for a rack according to a modification of the second embodiment of the present invention; and

[0039]FIG. 17 is a side view of the relay terminal box according to the modification of the second embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Hereinafter, a structure for introduction of electric cables into an explosion-proof facility according to the present invention will be described below in detail with reference to the attached drawings.

[0041]FIG. 4 is a front diagram showing the internal structure of an explosion-proof facility containing a gas turbine according to the first embodiment of the present invention. The explosion-proof facility is composed of a foundation section 1 b, a floor section 2, a gas turbine 3, an air inlet section 3 a, an explosion-proof building 4, a first rack 5, a relay terminal box 7, a generator 51 and a steam turbine 52, as shown in FIG. 4. The gas turbine 4 is installed in the explosion-proof building 4 which is blocked off or shielded from the outside thereof. The relay terminal box 7 is provided on the front wall of the first rack 5. The electric cables are introduced from the outside of the explosion-proof building 4 into the inside thereof through the relay terminal box 7.

[0042]FIG. 5 is a schematic cross sectional view showing the internal structure of the explosion-proof facility in the first embodiment of the present invention. Explosion-proof structure 100 is composed of an outer building 1 a built on the foundation section 1 b. The outer building 1 a defines an inner space 1 c. In the inner space 1 c, the floor section 2 is formed. An electric cable trench 2 a is provided on the side of the floor section 2. The gas turbine 3, the explosion-proof building 4, the first rack 5 and a second rack 6 are installed on the floor section 2. A sleeve 4 b is provided for a side wall between the explosion-proof building 4 and the first rack 5, and is an opening pipe for connecting the inside of the explosion-proof building 4 and the inside of the first rack 5. Sealing material is filled into the sleeve 4 b to block off the inside of the explosion-proof building 4 from the inside of the first rack 5, if necessary, after the introduction of the electric cables. The first rack 5 is used as a repeater of the electric cables to be distributed into the explosion-proof building 4. The second rack 6 is used as a repeater of fuel supplied into the explosion-proof building 4.

[0043] In the explosion-proof structure 100 of the first embodiment of the present invention, the explosion-proof building 4 has a structure in which disassembly and reassembly are possible. On the other hand, the first and second racks 5 and 6 have a structure in which disassembly is difficult. That is, even if the explosion-proof building 4 is disassembled, the first and second racks 5 and 6 remain without disassembly.

[0044]FIG. 6 is a schematic perspective view showing the installation condition of the relay terminal box according to the first embodiment of the present invention. Referring to FIG. 6, electric cable pipes 60 and the relay terminal box 7 are provided for the first rack 5. External electric cables 61 in the trench 2 a pass through the electric cable pipes 60, and are introduced into the relay terminal box 7. The external electric cables 61 are received by the relay terminal box 7 at openings 7 a. The external electric cables 61 are connected with internal electric cable 75 in the relay terminal box 7. A sleeve 8 is provided on the front wall of the first rack 5. The internal electric cables 75 are introduced from the relay terminal box 7 into the first rack 5 through the sleeve 8. The internal electric cables 75 are introduced from the first rack 5 into the explosion-proof space 4 a through the introduction pipe 4 b.

[0045] It should be noted that the inside of the sleeve 8 is filled with sealing material to shield the inside of the first rack 5 from the outside, after the introduction of the internal electric cable 75. In the same way, the inside of the introduction pipe 4 b is filled with the sealing material to seal the explosion-proof space 4 a from the first rack 5. When the explosion-proof building 4 is disassembled in accompaniment to maintenance of the gas turbine 4, the first and second rack 5 and 6 are left on the floor section 2 without disassembly. The introduction pipe 4 b is disassembled when it is a part of the explosion-proof building 4, but is left when it is a part of the first rack 5.

[0046]FIG. 7 is a front view of the first rack 5 and the relay terminal box 7 according to the first embodiment of the present invention. FIG. 8 is a side view of the relay terminal box 7 according to the first embodiment of the present invention. The relay terminal box 7 is installed on the front wall of the first rack 5. The relay terminal box 7 is composed of the openings 7 a, an upper fixing section 7 b and a lower fixing section 7 c. The relay terminal box 7 is installed on the front wall of the first rack 5 by the upper fixing section 7 b and the lower fixing section 7 c. The first to fourth sleeves 8 a to 8 d or more may be provided for the relay terminal box 7. First to fourth sleeves 8 a to 8 d extend into the first rack 5. Each of the sleeves 8 is composed of a first union 11, a first nipple 12, a sealing section 13, a second nipple 14, an elbow 15, a pipe 16, a second union 17 and a coupling plate 5 a. The sealing section 13 has an opening. The sealing section 13 is filled with the sealing material through the opening after completion of the introduction of the internal electric cable. The inside of the first rack 5 is shielded from the outside thereof by the sealing material.

[0047]FIG. 9 is a plan view showing the basic arrangement of six relay terminal boxes 7′ in the first embodiment of the present invention. The six terminal boxes are provided in accordance with the function and the type, for example.

[0048] Next, a modification of the first embodiment of the present invention will be described below with reference to FIGS. 10A and 10B.

[0049] Referring to FIGS. 10A and lob, in the explosion-proof structure 100 in which relay terminal boxes 7 and 7′ are installed, the external electric cables 61 in the trench 2 a extend through the electric cable pipes 60 which are buried in the floor section 2 and are connected to the relay terminal box 7 or 7′. The pipes 60 extend from the trench 2 a in a horizontal direction and extend in an upper direction below the first rack 5. The external electric cables 61 are connected with the internal electric cable 75 in the relay terminal box 7 or 7′. The internal electric cables 75 are introduced into the first rack 5 through the sleeves 8. The sealing section 13 of the sleeve 8 shields the inside of the first rack 5 from the inside of relay terminal box 7 or 7′.

[0050] It should be noted that first and second racks 5 do not protrude from the explosion-proof building 4 but are accommodated in the explosion-proof building 4.

[0051] Next, the introduction structure of electric cables in the explosion-proof facility according to the second embodiment of the present invention will be described below. Components that are the same as in the first embodiment are allocated with the same numerals as in the first embodiment.

[0052]FIG. 11 is a front diagram showing the internal structure of the explosion-proof facility such as a plant containing a gas turbine according to the second embodiment of the present invention. The explosion-proof facility is composed of the foundation section 1 b, the floor section 2, the gas turbine 3, the air inlet section 3 a, the explosion-proof building 4, the first rack 5, the second rack 6 (not shown), the first relay terminal box 7, the generator 51 and the steam turbine 52, as shown in FIG. 11. The relay terminal box 7 is provided on the side wall of the first rack 5. The first rack 5 is used as a repeater of the electric cables to be distributed into the explosion-proof building 4. The second rack 6 is used as a repeater of fuel supplied into the explosion-proof building 4.

[0053]FIG. 12 is a schematic cross sectional view showing the internal structure of the explosion-proof facility in the second embodiment of the present invention. FIG. 13 is a schematic perspective view showing the installation condition of the relay terminal box 7 according to the second embodiment of the present invention. The external electric cables 61 extending in the pipes 60 arranged on a tray 71 are introduced into upper openings 7 a′ of the relay terminal box 7 provided for the first rack 5, as shown in FIG. 13. The external electric cables 61 are connected with the internal electric cable 75 in the relay terminal box 7. The internal electric cables 75 are introduced in the first rack 5 through the sleeves 8.

[0054] In FIG. 13, the electric cable pipes 60 and the relay terminal box 7 are provided for the first rack 5. The sleeves 8 are provided below the terminal box 7 to extend into the first rack 5. Introduction pipes 4 b are provided between the first rack 5 and the explosion-proof building 4 to extend into the explosion-proof space 4 a of the explosion-proof building 4. The external electric cables 61 are arranged in the pipes 60 on the electric cable tray 71. The external electric cables 61 are introduced into the relay terminal box 7. The external electric cables 61 and the internal electric cables 75 (Teflon electric cable) are connected to each other in the relay terminal box 7. The internal electric cables 75 are introduced inside the first rack 5 through the sleeves 8. In the first rack 5, the internal electric cable 75 is introduced into the explosion-proof space 4 a through the introduction pipe 4 b.

[0055] It should be noted that the inside of the sleeve 8 is filled with sealing material to seal the inside of the first rack 5 from the outside, after the introduction of the internal electric cables 75. In the same way, the inside of the introduction pipe 4 b is filled with the sealing material.

[0056]FIG. 16 is a front view showing a relay terminal box 7′ according to a modification of the second embodiment of the present invention. FIG. 17 is a side view showing the relay terminal box 7′ according to the modification of the second embodiment of the present invention. In this modification, sleeves 9 are used to introduce the internal electric cables from the relay terminal box 7′ into the first rack 5 in place of the sleeves 8. The sleeves 9 are provided above the relay terminal box 7′ on the side wall of the first rack 5.

[0057] The relay terminal box 7′ is installed on the front wall of the first rack 5. The relay terminal box 7′ is composed of the lower openings 7 a, upper fixing section 7 b′ and lower fixing section 7 c′. The relay terminal box 7 is installed on the side wall of the first rack 5 by the upper fixing section 7 b and the lower fixing section 7 c. The first to fourth sleeves 8 a to 8 d or more may be provided for the relay terminal box 7. The first to fifth sleeves 9 a to 9 e extend into the first rack 5. Each of the sleeves 9 is composed of a first union 21, a first nipple 22, a sealing section 23, a second nipple 24, an elbow 25, a pipe 26, a second union 27 and a coupling plate 5 a. The sealing section 23 has an opening. The sealing section 23 is filled with the sealing material through the opening after completion of the introduction of the internal electric cable. The inside of the first rack 5 is shielded from the outside thereof by the sealing material. It should be noted that introduction sections 5 b and 5 c are provided for the first rack 5. For example, these introduction sections 5 b and 5 c are used as wiring routes for the electric cables which are introduced into the first rack 5 but are not introduced into the explosion-proof building 4.

[0058] The relay terminal box 7, 7′ according to the first embodiment of the present invention is arranged outside the explosion-proof building 4. Therefore, the relay terminal box 7, 7′ needs not to be an explosion-proof relay terminal box. Also, the electric cables introduced from the relay terminal box 7, 7′ into the explosion-proof building 4 are the internal electric cables in the above embodiments. Therefore, it can be avoided that any electric cable other than the internal electric cables is introduced into the explosion-proof building 4. Further, in the present invention, a construction which buries the electric cable pipes in the floor section is unnecessary. Therefore, the time and cost of the construction can be reduced.

[0059] It should be noted that the above embodiments and modification can be applied in combination in a range where contradiction is caused.

[0060] In the electric cable introduction structure in the explosion-proof facility according to the present invention, buried pipe is not used for the introduction of the electric cable. Therefore, it is not necessary to consider and work for the introduction of the electric cable in the step of the foundation work. Also, the situation does not occur in which many buried pipes are buried. Therefore, interference between the buried pipes and the reinforcing rod of concrete does not occur.

[0061] Moreover, the determination of electric cable introduction routes can be carried out in accompaniment with the building of the explosion-proof building. Therefore, it is not necessary to consider the electric cable introduction route at an early stage of the construction when the foundation work is carried out. 

What is claimed is:
 1. A method of constructing a structure for introduction of an electric cable, comprising: constructing an explosion-proof building on a foundation shielded from the outside to accommodate a gas turbine such that said explosion-proof building can be disassembled and re-assembled for maintenance of the gas turbine; constructing a rack in contact with said explosion-proof building along a wall of said rack such that said rack is not disassembled when said explosion-proof building is disassembled; attaching a relay terminal box on an other wall of said rack; connecting an external electric cable to an internal electric cable which extends from the gas turbine apparatus into said relay terminal box with said relay terminal box; and providing sealing for said internal electric cable to seal said rack from said explosion-proof building.
 2. The method of claim 1, further comprising providing further sealing for said internal electric cable to seal between said relay terminal box and said rack.
 3. The method of claim 2, wherein the further sealing is provided at a portion of the other wall of said rack above said relay terminal box.
 4. The method of claim 2, wherein the further sealing is provided at a portion of the other wall of said rack below said relay terminal box.
 5. The method of claim 1, further comprising: constructing a trench in a portion of said floor section adjacent to said explosion-proof building; and arranging said external electric cable in said trench and introducing said external electric cable into said relay terminal box from said trench.
 6. A maintenance method in which: an outer building formed on a foundation section, an explosion-proof building is in said outer building on a floor section formed on said foundation to accommodate a gas turbine, a rack is in contact with said explosion-proof building, and a relay terminal box is formed on a wall of said rack not in contact with said explosion-proof building, wherein said relay terminal box connects an external electric cable with an internal electric cable which extends from said gas turbine into said relay terminal box, and wherein sealing is provided for said internal electric cable to seal between said explosion-proof building and said rack; said method comprising: disassembling said explosion-proof building for maintenance of said gas turbine without disassembling said rack; and reassembling said explosion proof building after said maintenance.
 7. The method of claim 6, wherein further sealing is provided for said internal electric cable to seal between said relay terminal box and said rack.
 8. The method of claim 6, wherein said further sealing is provided at a portion of the wall of said rack below said terminal box.
 9. The method of claim 6, wherein said further sealing is provided at a portion of the wall of said rack above said terminal box.
 10. The method of claim 6, wherein said further sealing is provided at a portion floor section adjustment to said explosion-proof building and said external electric cable is arranged in said trench and introduced into said relay terminal box from said trench. 